JOI 2016 Open Contest Skyscraper
Difference between en2 and en3, changed 2 character(s)
[Problem Statement](http://s3-ap-northeast-1.amazonaws.com/data.cms.ioi-jp.org/open-2016/2016-open-skyscraper-en.pdf)↵

Abridged Problem Statement : Given $a_1, a_2, ..., a_n$, find the number of permutations of these numbers such that $|a_1 - a_2| + |a_2 - a_3| + ... + |a_{n - 1} 
+- a_{n}| \le L$ where $L$ is a given integer.↵

The [editorial](http://s3-ap-northeast-1.amazonaws.com/data.cms.ioi-jp.org/open-2016/2016-open-skyscraper-sol-en.pdf) given is quite brief and the sample code is nearly unreadable. I have no idea how to do the dp.↵

Can anyone explain the solution? Thanks.

History

 
 
 
 
Revisions
 
 
  Rev. Lang. By When Δ Comment
en4 English zscoder 2016-06-25 17:28:19 161
en3 English zscoder 2016-06-25 15:49:45 2 Tiny change: 'a_{n - 1} + a_{n}| \l' -> 'a_{n - 1} - a_{n}| \l'
en2 English zscoder 2016-06-22 12:11:00 12
en1 English zscoder 2016-06-22 12:06:45 623 Initial revision (published)